Techniques and Tips for SMAW Operation

Techniques and Tips for SMAW Operation

Summary:

In general, the operator factor, or the percentage of operator’s time spent laying weld, is approximately 25%. The rest is spend in preparation and in removing slag.

The actual welding technique utilized depends on the
electrode, the composition of the workpiece, and the position of the
joint being welded.

The choice of electrode and welding position also determine the welding speed.

Flat welds require the least operator skill, and can be done with electrodes that melt quickly but solidify slowly.

This permits higher welding speeds. Sloped, vertical or
upside-down welding requires more operator skill, and often necessitates
the use of an electrode that solidifies quickly to prevent the molten
metal from flowing out of the weld pool.

However, this generally means that the electrode melts less quickly, thus increasing the time required to lay the weld.

SMAW Operation Set-up

Before starting make sure that you are using a helmet for SMAW welding as well as protective clothing.

Clean the workpiece

Clamp the work close to the weld

Insert the electrode into the insulated holder holder. Set amperage at levels recommended by the electrode manufacturer.

Determine the best arc length. As a guideline the arc for a 1/16" to 3/32" diameter electrode is 1/16" (1.6mm). The arc lengh for a 1/8" and 5/32" electrode is 1/8" (3mm).

Have a chipping hammer available to remove any slag and before doing a 2nd pass with the weld.

Stick Welding Examples Diagram

Poor weld bead characteristics include large spatter deposits, use of the wrong arc, higher/lower amperage levels than recommended and poor penetration.

Operation

Starting the Arc

Scratch Start Technique:

To strike the
electric arc when starting a SMAW operation, the electrode is brought into contact with the workpiece,
dragged like lighting a match, and then pulled away slightly.If the arc
lights and then goes out, that means the electrode was pulled too far
away from the base metal. If the electrode sticks to the metal, give a
twist and it should come free.

Tapping Technique:

Move
the electrode straight down to the base metal. Then lift slightly. The
arc should start. If the arc goes out, that means it was lifted too high
off the workpiece.

Operating the Electrode Holder

This initiates the melting of the workpiece and the
consumable electrode, and causes droplets of the electrode to be passed
from the electrode to the weld pool.

As the electrode melts, the flux covering disintegrates, giving
off a vapors that protect the weld area from oxygen and other
atmospheric gases.

In addition, the flux provides molten slag which covers the filler metal as it is travels from the electrode to the weld pool.

Once part of the weld pool, the slag floats to the surface and protects the weld from contamination as it solidifies.

Groove (Butt) Joint Welding

Tack Welds

Tack Weld

Photo Credit: Miller Welds

Tack weld the two pieces of metal to hold them in place. This will reduce joint distortion, which is caused by the expansion and contraction of metal as it is heated and cooled.

Double V-Groove, Single V-Groove and Square Groove Welds

When performing a groove weld, hold the electrode perpendicular to the weld. Lean the electrode in the direction of the weld.

A
single string bead is all that is needed for a narrow groove weld
joint. For wider groove weld, then a weave bead or many stringer beads
is a better option.

Square Groove Weld

Photo Credit: Miller Welds

Square Groove Weld

If thickness of materials are 3/16" (5MM) they can usually be welded with a square groove weld and no prep.

Single and Double V-Groove Welds

Photo Credit: Miller Welds

V-Groove

For SMAW operation welds that require thicker metals it may require that edges are prepared (v-groove) of butt joints for good welds.

V-groove
is recommended for metal thickness of 3/16" to 3/4" (5 to 19mm). It is
also used for any thickness when welding can only be done from one side.

The bevel can be created (at 30 degrees) using a grinder, or
plasma or oxyacetylene cutting equipment. After creating the bevel
remove scale.

T-Joint Welding

Fillet Weld

Tee Joint

The electrode (1) should be kept at a 45 degree angle or less when creating a fillet weld.
Photo Credit: Miller Welds

For a fillet
weld, hold the electrode at a 45 degree angle or less to the weld. Lean the
electrode 10 degrees to 30 degrees in the direction of the weld.

Use a short arc and move at a steady speed. For upright sections weld both sides.

When necessary for strength add a second layer (remove slag before adding another layer).

Move the electrode using a circular motion.

Lap Joints

Tee Joint

When Applying A Single Layer or Multi-Layer Welding Pass Move The Electrode In A Circular Motion
Photo Credit: Miller Welds

When welding a lap joint the electrode should be held at a 30 degree angle or less. Use one or two weld passes as needed. Before the second pass remove any slag.

Welding Positions

Each welding position is described below. Note that not every electrode is right for each position. Check the manufacturers directions before proceeding with any SMAW operation.

Horizontal

Single Pass Bead Weld

When Doing A Horizontal Weld The Welder Needs To Take Account Of Distortion Caused By Gravity
Photo Credit: Miller Welds

The issue with the horizontal welding is the distorting effect gravity will have on the weld pool. If necessary or if it will help, tack weld a backing strip. Beveled edges can also be of help.

When welding during the SMAW operation keep the electrode at 90 degrees to the weld. Lean into the weld direction by 15 degrees.

Materials Beveled For Horizontal Weld

Photo Credit: Miller Welds

Multi-Pass Weld Locations

Each Number Indicates the Location of Each Weld Pass. Note use of a backing plate. Slap must be removed after each weld.
Photo Credit:Miller Welds

Vertical Welding Position

Multi-Pass Vertical Weld Diagram

Illustration of Welding Direction and Location of Each Weld Pass When Completing A Vertical Weld
Photo Credit: Miller Welds

The weld direction can move from top to bottom or bottom to top. It is easier to weld in an upward direction.

Use a tack welded backing plate if needed and for thicker materials bevel the edges.

Hold the electrode at 90 degrees to the material being welding.

Vertical Tee Joint Welding Diagram

Be Aware of The Distorting Effect of Gravity. Weld The Joint on Both Sides to Maximize Strength. Use a Weaving Motion When Traveling Along The Weld With the Electrode.
Photo Credit: Miller Welds

Lap Joint Weld Diagram

Photo Credit: Miller Welds

Overhead Welding Position

Overhead Welding Position

Miller Welds

For an overhead weld the arc should be positioned slightly away an dout from the crater. Tack weld a backing plate and use beveled edges if necessary.

Overhead Groove Joint Diagram

Photo Credit: Miller Welds

Overhead Tee Joint

Miller Welds

Testing the Weld

Weld Strength Test Diagram

Test Welds Using a Hammer In The Direction Shown Above. Weakness Can be Due to Porosity (holes in the weld), Incorrect Heat or Fast Travel Speed.
Photo Credit: Miller Welds

Use a hammer to strike the joint on the material welded to the base. The weld should bend slightly and not break. Breakage could be due to too many holes (porous) in the weld, or if the weld contains slag. Also note if any of the beveled area is visible. If it is, this could indicate that the filler material was not fully melted due to traveling too fast with the electrode or by not using enough heat.

Slag Removal

Once hardened, it must be chipped away to reveal the
finished weld. As welding progresses and the electrode melts, the welder
must periodically stop welding to remove the remaining electrode stub
and insert a new electrode into the electrode holder.

This activity, combined with chipping away the slag,
reduce the amount of time that the welder can spend laying the weld,
making SMAW one of the least efficient welding processes.